1. Field of the Invention
The present invention generally relates to pathology and microscopy and more particularly relates to improvements in quality assurance for pathology using digital microscopy.
2. Related Art
The diagnosis of glass microscope slides by a pathologist is known to be subjective. Many factors contribute to this lack of objectivity, including the training and skill of the pathologist and the quality of the glass slides from which the diagnosis was made. While use of tissue processing instruments and automatic staining equipment has increased the quality and consistency of slide preparations, a significant portion of glass slides that are read by pathologists are still suboptimal and may contribute to inaccurate interpretations.
One of the possible contributing factors to the subjectivity of reading pathology slides is the lack of standardization of the microscope, a tool that has been in use for hundreds of years and which is not recognized as an approved medical device. Pathologists are free to use whatever microscope they want to read glass slides and are expected to know how to keep their microscope in optimal (Koehler) alignment, what objectives lenses with what numerical apertures are best suited for different specimen types, and to be aware when the bulb in their microscope needs to be replaced (because the color temperature of the illuminating light will change the color in the image they observe through the microscope). Many pathologists' microscopes are not maintained in optimal working condition or furnished with optimal objective lenses, thus compromising spatial details and color fidelity that may be essential to making more accurate diagnoses.
Another likely contributing factor to the subjectivity of pathology is deficiencies in glass slide quality, which can include over- or under-staining (i.e., too dark or too light), tissue folds, sections that are too thick or too thin, bubbles, debris as well as variations in image quality observed between slides prepared by different autostainers. There is little a pathologist can do to overcome the challenges of a poorly prepared glass slides (“garbage in/garbage out”), other than to try to make adjustments in the optical properties of the microscope (adjust condenser, increase/decrease light) to try and ameliorate glass slide quality problems.
Referring to FIG. 1, a flow diagram illustrating a conventional process for quality assurance using glass slides is shown. Initially, in step 100 a glass slide is prepared and then in step 110 the quality of the slide is inspected and assessed. In a typical laboratory, a histotechnologist screens the glass slides to assess slide quality, as shown in step 120, and rejects sub-optimal slides before they are read by a pathologist. Rejected slides result in re-cuts and the preparation of new, presumably higher quality, glass slides. In some cases, the slides can be fixed, e.g., by restaining if the staining is too light. This is shown in step 130. Finally, when a glass slide is acceptable, the slide is reviewed and interpreted by a pathologist in step 140.
This conventional process suffers from the inability of the histotechnologist to carefully review every area of a glass slide (some labs process hundreds or thousands of slides every day). The conventional process additionally suffers from the increasing shortage of qualified histotechnologists, and pressure on laboratories to continually improve productivity. Furthermore, the overall aging of the population and the associated increased incidence of cancer (and surgical biopsies) only exacerbate the challenges of quality-assuring glass slides before they are read by a pathologist due to the significant increase in the number of glass slides that are prepared.
Therefore, what is needed is a system and method that overcomes these significant problems found in the conventional systems as described above.